Resistance Training - When did you begin after surgery?
I was walking from day 1. All else I was doing 2 weeks out after my 2 week follow-up. I did talk with my doc about it. He advised to go slowly and if anything bothered me to stop. I was given the same advice regarding body weight exercises (squats, etc..). Add them in slowly and stop if uncomfortable. Anything that challenged my core I didn't get to until 5 or 6 weeks out (even push-ups, etc....). I would certainly run anything by your doc before starting. The key for me and my doc was to stay within the no lifting over 15 pounds limit.
I started pilates--which is resistance training--at 4 weeks out. I added swimming and water aerobics to that today, a little over 6 weeks out. In another month or two I may add some sessions with a personal trainer doing more conventional weight training.
I will say this: don't push yourself. I did not anticipate how much down time I was going to need to recuperate from surgery. Here I am at 6 weeks plus, and I'm still needing naps every other day or so, plus a good 9-10 hours' sleep every night. So I would suggest going at things slowly, meaning do what you want to do, but do no more than feels absolutely ok. It's really easy to overestimate our ability to recover, but it really was major surgery, so go easy.